Public Information Statement
Issued by NWS Miami, FL

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NOUS42 KMFL 071908

Public Information Statement
National Weather Service Miami FL
303 PM EDT Wed Apr 7 2021

To:        Subscribers:
           -NOAA Weather Wire Service
           -Emergency Managers Weather Information Network
           Other NWS Partners and NWS Employees

From:      Allison Allen, Chief
           Marine, Tropical and Tsunami Services Branch

Subject:   Hurricane Threats and Impacts (HTI) Mosaic Testing on
           April 8, 2021 (Backup date: April 22, 2021)

The NWS Weather Forecast Office (WFO) in Honolulu and WFOs in the NWS Southern Region and in the NWS Eastern Region will commence with Hurricane Threats and Impacts (HTI) threat grid mosaic testing on Thursday, April 8.  Thursday, April 22 has been designated as the backup test date in the event that testing cannot be conducted on April 8.

Testing will begin at approximately 1500 UTC.  Test activities will take approximately 1 hour; however, NWS dissemination systems may take up to an hour and a half to purge all test data.  All test data is expected to be cleared by 1730 UTC.

For the test, HTI grids will be created for Hurricane Wind Threat, Hurricane Storm Surge Threat, Hurricane Flooding Rain Threat, and Hurricane Tornado Threat.  These grids are sent to the National Digital Forecast Database (NDFD) and can be seen on the NDFD web viewer at:

The Product Description Document for these threat grids can be found here:

HTI grids are created by WFOs for their county warning area and mosaicked together to form a more geographically consistent depiction of the threat posed by hurricane hazards.  The HTI mosaics can be found in kml format at:

When populated HTI grids are posted, they also can be found on the WFO Tropical Web Portal page linked below under the Threats and Impacts tab:

Periodic software and hardware testing in preparation for tropical cyclone events will continue during the remainder of 2021.

For more information, please contact:

  Pablo Santos
  Meteorologist in Charge
  National Weather Service Office
  Miami, FL, 33165


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